1. Field of the Invention
The present invention relates to a recording disc cartridge. More particularly, it relates to a recording disc cartridge such as a magnetic disc cartridge and a magnetic optical recording disc cartridge comprising a disc containing a lubricant.
2. Description of Related Art
A magnetic disc cartridge has an opening in a case so as to slide the magnetic disc against a magnetic head. However, dust entering the case from the opening in the case or particles generated by sliding of the disc against the magnetic head adhere on the surface of the disc so that the electromagnetic conversion characteristic of the disc is reduced. To prevent adherence of the dust and the particles, a liner is provided between the disc and the case so that the linear contacts the surface of the disc and wipes off the dust and the particles. One conventionally used liner is made of a non-woven fabric produced by dispersing polypropylene is a matrix of rayon lint and melting polypropylene to bind the rayon fibers together.
The magnetic disc is required to have good durability since it slides on the magnetic disc at a high relative speed during recording and reproducing. To improve the durability of the magnetic disc, liquid paraffin is usually added in a magnetic layer of the disc. The liquid paraffin exudes from the magnetic layer and is contained in the liner in the case. Then, the praffin is continuously supplied to the surface of the magnetic disc in use to reduce a coefficient of friction between the disc surface and the magnetic head, and thereby the durability of the disc is improved (cf. U.S. Pat. No. 4,223,361).
Recently, the thickness of the magnetic layer of the disc has been thinner and thinner in order to increase the recording density, and therefore, the absolute amount of lubricant to be contained in the magnetic layer decreases. Thus, the small amount of liquid paraffin cannot impart enough durability to the magnetic disc.
It has been proposed to use an aliphatic acid compound such as an aliphatic acid or its derivatives as the lubricant to be contained in the magnetic layer of the magnetic disc in order to maintain the necessary durability of the disc even when the magnetic layer is thin enough for high recording density. However, the aliphatic acid compound lubricant causes drop out when the magnetic disc with the aliphatic acid compound is used in the case using the conventional liner.